Katz is a mench he'd most likely write you back. But he is also a busy guy. If you tell him what the discussion is about on the forum I'm sure he will at least have some thoughts on the subject. I forget what monitors he uses as a reference. B&Ws?

this approach is just less popular but it doesn't follow that being less popular it is as such not "reasonable" and only "idiosyncratic and subjectively reported" either that those more popular approaches are in contrast "reasonable" and not only "idiosyncratic and subjectively reported"

they are just traditional and believed to be reasonable

That's correct and Toole argues that additional lateral reflections are preferrable for recreational listening - even for professionals. But again you have to ask what reality looks like. Only few engineers use different control rooms for recording (critical listening) and mixing (make it sound "right" so the recording "translates" well into any listening room). I doubt that anybody is capable of rating how a recording will sound like in various domestic listening spaces while mixing in a quasi anechoic "non-environment" control room (worst case). As a result the recording is made for the control room acoustics and not for any other space.

That expands the discussion to another interesting point: music changes with the space it's played in. Church music, music for concert halls, music of cultures living outside. So "realistic sounding" might not be stereo's purpose at all.

Do mastering engineers have any influence on what we are talking about, other than contributing their opinion? Most of us will never have the chance to listen to a track before and after mastering, but I can't believe it has any influence on imaging.

Unfortunately mastering affects the spatial attributes heavily. Adding compression and all sorts of "esoteric" effects has become standard practice.

Maybe it's these effects I dislike about some "synthetic" recordings. Can you tell me some studio productions that in your opinion are very high quality in terms of mixing/reverb and purist in terms of mastering? No hit-parade stuff, please.
I prefer testing to citing books.

Do mastering engineers have any influence on what we are talking about, other than contributing their opinion? Most of us will never have the chance to listen to a track before and after mastering, but I can't believe it has any influence on imaging.

Yes.

Compressors can squash the depth out of recordings or bring them to a nice coherent pleasing level depending on how it's used or if it's needed in the first place.

EQ will have an effect on depth of the recording as well. If all they are thinking about is filling in the spectral content often you will hear recordings depth of field squashed out by high end boosts. As a sound gets further away there will be less high end and less bass generally.

MS Processing can be used which can even out the spaciousness or distort it.

It's hard to say that these things are bad exactly though. They are just tools. Dry unprocessed recordings can seem less realistic and basically underwhelming imo.

Problems in the control rooms can have an effect on the end recording as well. If the control room attenuates the way the high end is perceived this will show up as the inverse in the end recordings - overly bright spectral balance. This is the same for any other thing that the engineer is trying to control. If the room exaggerates the ambiance then the end recording might end up too dry or vice versa.

even though mostly wave guide designs with narrow dispersion
are referred to as "Constant Directivity", there are more
techniques capable of a more or less frequency independent
directivity (in a certain frequency range). Even wave guides
cover only a certain bandwidth.

An well working omni-source is in fact a constant directivity
source. In my understanding the term means directivity to
be independent from frequency nothing more and nothing less.

Even a "Wide Dispersion" system can be "Constant Directivity".

There are dipole OB designs of appropriate driver and baffle sizing
which meet the criteria quite well, also semi open bass and midrange
cabinets with kardioid dispersion.

As i mentioned before also distributed mode loudspeakers can
be made "large bandwidth constant directivity".